1. Field of the Invention
The invention pertains to a relief valve for being arranged on an opening of a fuselage shell of an aircraft, to a fuselage part with such a relief valve for being installed into an aircraft fuselage with a fuselage shell and a plurality of fuselage frames arranged on the inside of the fuselage shell, and to an aircraft fuselage with such a fuselage part.
2. Description of the Related Art
From U.S. Pat. No. 4,174,083 a device for influencing the air flow on a cover of a fuselage is known for increasing the supply of ram air in a climate system.
The general state of the art includes relief valves or “negative relief valves” (Negative Relief Valves) for being arranged on an opening of a fuselage shell of an aircraft that serves for producing a fuselage part or an aircraft fuselage. One such relief valve is intended for being installed into an aircraft fuselage with a fuselage shell and a plurality of fuselage frames arranged on the inside of the fuselage shell, wherein this relief valve is integrated into the aircraft system and forms part of a cabin pressure control system (Cabin Pressure Control System) for compensating a negative cabin pressure relative to the external pressure on the skin of the fuselage while the aircraft is in flight. The installation site of the relief valve depends on the type of aircraft and, among other things, external constraints such as, for example, the float line of the aircraft and the accessibility. In most known applications, these valves are installed into the skin of the aircraft in the front fuselage section. In case of a negative cabin pressure (relative to the external pressure), these valves open and allow a pressure compensation between the cabin and the surroundings due to the mass flow through the valve.
Relief valves of this type, one embodiment of which is illustrated in FIGS. 1 to 4 and identified by the reference symbol 10′, are arranged on a fuselage part 1′ with a shell part 3′. A plurality of fuselage frames 7a′, 7b′, 7c′, 7d′ extending in or along the circumferential direction of the aircraft fuselage is arranged on the inside of the shell part 3′. FIG. 1 shows the inside of the shell part 3′ with sections of the fuselage frames 7a′, 7b′, 7c′, 7d′. The shell part 3′ features an opening 9′ that is covered by a cover 13′ of the relief valve 10′, wherein this cover is coupled to the shell part 3′ by means of a hinge joint 11′ such that the cover 13′ can be closed or opened. The hinge joint 11′ is situated on the side of the opening 13′ that faces the flow S flowing around the fuselage part 1′ installed into an aircraft fuselage in the flow direction S, i.e., on the front edge referred to the longitudinal aircraft axis X or the longitudinal direction X1 of the feel of part 1′. The cover 13′ is prestressed into the closed position (FIG. 2) against a stopping device 15′ by means of a prestressing device. In FIGS. 2 and 3, the prestressing force exerted by the prestressing device is indicated with an arrow and the reference symbol “F” referring thereto. The relief valve 10′ is illustrated in an opened position in FIG. 3. In the opened position of the relief valve 10′, part of the flow flowing around the fuselage part 1′ in the flow direction S reaches the interior of the aircraft fuselage, into which the fuselage part is integrated. This means that the relief valve 10′ known from the general state of the art opens when the pressure on the outside of the fuselage that is subjected to a flow S lies above the pressure on the inside of the relief valve 10′ by a certain amount such that a pressure compensation takes place in the interior of the fuselage as intended in these situations.
Although the relief valve 10′ known from the general state of the art has a simple construction, the pressure compensation does not always take place sufficiently fast.